A Multiple Function Peripheral (MFP) of the related art includes a sheet post-processing device that post-processes sheets transported from an image forming device. The sheet post-processing device includes a processing tray that holds the sheets for post-processing of the sheets, inlet rollers through which the sheet is input from the image forming device, and outlet rollers that output the sheet input from the inlet rollers to the processing tray. The sheet post-processing device controls a transport speed of the sheet when discharging the sheet from the outlet rollers to the processing tray. The control of the transport speed is performed at timing near the exit of a trailing end of the sheet from the outlet rollers after a leading end of the sheet comes into contact with the processing tray. In addition, in the transport speed of the sheet, there are a first transport speed that is a speed for transporting the sheet and a second transport speed (first transport speed>the second transport speed) that is a speed suitable for discharging the sheet to the processing tray. The sheet post-processing device performs control to decelerate the transport speed of the sheet from the first transport speed to the second transport speed in the vicinity of the exit of the trailing end of the sheet from the outlet rollers. However, in the control of the transport speed of the sheet in such a sheet post-processing device, the speed (=first transport speed) of the sheet in the middle of discharging the sheet from the outlet rollers to the processing tray is large and the sheet may be buckled and the like. Thus, positions of the sheets discharged on the processing tray may be varied.